Friday, July 28, 2017

Retro Post: Fresh Water System

As I'm in the midst of rebuilding a few parts of the Astrolander interior, including the fresh-water system, I realized I never properly documented "Version 1". Time for a Retro Post.

Fresh water is always needed in a camper. With as much time as we spend in the desert, having a big supply of water isn't really optional. Technically speaking, a 12-gallon tank is barely adequate for 2 days, if we stick to the 2-gallon per person per day rule. (Don't worry, we supplement with bottled water and a 5L "Jerry Can" for longer trips.)

Given the construction of our Craigslist-sourced conversion-van bench/bed, we had just over 8" of clearance underneath for a tank. Fortunately, Valterra makes this line of excellent ABS tanks. Each tank is 8" by 16" by "X", where X is some incremental length from 9" to 72". It happens that 8 x 16 x 24" fits very nicely in the available space, and nets out 12 gallons.

The real advantage of the Valterra tanks, from the DIY perspective, is that they're ABS - meaning it's very simple to put fittings, fill-spouts, etc. anywhere you like. Compared to Polyethylene tanks that require specialized equipment to make fittings, this is a cheap and easy way to build a "custom" tank to fit your needs.
Here, I'm marking out for a fill port.

Once I've located it, a simple hole saw is all I need. Drill and clean up the hole (getting as much of the swarf out of the tank as possible), then simply attach the fitting with ABS "glue". (Which is technically a solvent that "melts" the ABS, so you're chemically welding the two pieces together.)

Other parts of the tanks come with pre-molded bungs, but they're sealed from the factory. Temporarily adding a short nipple into the bung lets you drill out the plug without risking buggering up the threads.

Once all the bungs are in place, push-lock fittings and clear tubing are easy to plumb up.
Here you can see the vent-line (center), along with a "sight-gauge" on one end that lets me visualize the water level, even though the tank is opaque. The fill-port and gauge are oriented so that they're easily accessible from behind the seat. I'll be able to fill by running a hose in through the rear doors.

Here's a quick little test. I was really hoping to keep things super simple. This was to check the performance of just having a valve, no pump. The results were, predictably, underwhelming. There's just not a lot of head pressure here.

I chose this valve because it's a flange-mount, figuring that would make it easy to join to whatever cabinet/housing I came up with.

Also needed was a way to keep the tank from shifting. Here I'm bending up a steel retaining bracket that will constrain the tank underneath the seat.

I knew I'd be keeping the faucet as a drain anyhow, so I pressed forward with a design for how to mount things at the slider-door. Mocking up in cardboard is my default design process. I stopped here, while waiting for the hand-pump to arrive from Amazon.

Once the Rocket Hand Pump arrived, I moved quickly to plywood. The hand pump is plumbed into a "tee" from the same line that feeds the faucet. This way, I can (slowly) drain the tank on gravity-only, or pump out water as needed. No electric pump again keeps things simple, though I'll admit filling the wash basin for dishes or refilling large drinks bottles gets tiresome!

And here's how we usually end up when we're camping. The pump at the slider ends up as our "Water Bar", complete with flavor mixers, so as to encourage everyone to stay hydrated. The plastic step area is sufficiently waterproof that the occasional dribble from the faucet isn't an issue, though I do run a short length of hose from the nipple if I'm draining the tank.

The fire extinguisher was eventually relocated to the driver's seat area, but you can see the butterfly latch that holds down the "hatch". I made the rear portion of the mini-cabinet removable. It allows me to easily access the plumbing bits for service, but there's also enough space behind that area between the seat and the wheel well for me to store the coiled fresh-water fill hose and water-treatment supplies. Pop the hatch, pull out the hose, and I'm ready to fill the tank. The yellow cap is just to keep the valve clean and spider-free!

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